1. Field of the Invention
The invention relates to a recording medium for use in ink jet recording, digital electrophotographic recording, sublimation transfer recording, heat-sensitive recording, and thermal transfer recording methods, and to a method for manufacturing such a recording medium.
2. Description of the Related Art
Various information processing systems have recently been developed along with rapid progress in information technology industries, and recording methods and recording apparatuses suitable for these information processing systems have been developed and put into practice.
Among these recording methods, ink jet recording methods have been widely used in homes as well as in offices, since these methods are advantageous in that they can be used to record images on various recording materials, in that printers for the methods are inexpensive and compact, and in that the methods are very quiet.
Resolution of ink jet printers has been increasing in recent years, and it has become possible to obtain “photorealistic” recorded matter with high image quality. Along with such improvements in the ink jet printers, various kinds of ink jet recording sheets have been developed.
Characteristics required for these ink jet printing sheets are generally the following items: (1) rapid drying (rapid ink-absorbing speed), (2) proper and uniform diameter of ink dots (no bleeding), (3) good granularity, (4) high circularity of dots, (5) high color density, (6) high chroma (being free of dullness), (7) good water resistance, light fastness and ozone resistance of printed portions, (8) high brightness of recording sheets, (9) good storability of recording sheets (no yellowing or bleeding of images even in long-term storage (excellent in prevention of bleeding over time), (10) substantially no deformation with good dimensional stability (sufficiently small curling), and (11) good running property in ink jet printers.
To use the ink jet recording sheets as photographic glossy paper sheets for obtaining photorealistic high-quality printed matter, the recording sheets are also required to have glossiness, surface smoothness and texture of printed paper sheets resembling that of silver salt photographs as well as the aforementioned characteristics.
An ink jet recording medium with an ink receiving layer having a porous structure has been developed and put into practice in recent years to improve the aforementioned characteristics. Such an ink jet recording medium has excellent ink receptivity (rapid drying ability) due to the porous structure, and high glossiness.
Moreover, use of organic acid has been proposed to improve image storability such as light fastness and gas resistance, and storability of recording sheets (for example, see Japanese Patent Application Laid-Open (JP-A) Nos. 2001-191639, H10-193779, H10-264506 and H06-316145). However, it has become clear that inclusion of organic acid in an image receiving layer results in formation of an image with decreased density.
Improvement of image storability and storability of recording sheets, and prevention of a decrease in color forming density are required for not only ink-jet recording media having an ink receiving layer, but also for digital electrophotographic recording media having a toner receiving layer, sublimation transfer recording media having a sublimation transfer image receiving layer, heat-sensitive recording medium having a heat-sensitive color-forming layer, and thermal transfer recording media having a thermal transfer image receiving layer.
Accordingly, there is a need for an image recording medium that has high storability and on which an image with high storability and high density can be formed and for a method for manufacturing such an image recording medium.